用抗独特型单抗体外诱发抗天花粉蛋白的二次抗体应答

在前阶段工作中已获得16个抗天花粉蛋白的单抗。用其中的一个IgE类单抗TE 1免疫Wistar大鼠,通过大鼠-小鼠杂交瘤技术得到了抗独特型单抗。现研究抗独特型单抗AId 6c5在体外诱发二次抗体应答中所起的作用。实验结果表明:1.当将AId 6c5和天花粉蛋白初次免疫8周后的小鼠脾细胞和肠系膜淋巴结细胞一起培养时,能引起二次抗体应答,说明AId 6c5能代替抗原的刺激作用,如果培养系统中同时存在AId 6c5和天花粉蛋白(其剂量能引起体外二次抗体应答),则可出现某种程度的抑制。由于AId 6c5是单克隆抗体,提示一种AId能在不同情况下起刺激或抑制作用。3.应用竞争结合试验阐明AId 6c5除和TE 1外,还和另外两个单抗——TE 4(IgE)和2 A1(IgG1)——起反应,先前的工作证明这三个单抗和另外4个单抗都识别天花粉蛋白上的同一抗原决定簇。但AId 6c5对识别这同一决定簇的其余4个单抗反应很弱。以上说明a.IgE和其它Ig类别具有共同或交叉的独特型,b.也说明识别同一决定簇的IgE具有不同的独特型。4.将TE 1等三个单抗和AId 6c5预先作用后能抑制这三个单抗和天花粉蛋白的结合,说明AId 6c5所识别的独特型,位于抗原结合部位内,至少??是很靠近抗原结合部位的。

IN VITRO INDUCTION OF SECONDARY ANTI-TRICHOSANTHIN ANTIBODY RESPONSES BY ANTIIDIOTOPE ANTIBODIES

Trichosanthin (TCS),a purified protein of24K,is the active component of a Chinese tra-ditional medicine for abortion induction.Inprevious work we developed 16 anti-Tricho- santhin monoclonal antibodies.One of the 16MoAbs,TE1 of IgE class,was used to im-munize Wistar rats.Through the use of rat-mouse hybridoma technique,antiidiotope an-tibodies were raised.The regulatory effectsof one cloned antiidiotope antibody,AId_6C_5,were studied in vitro (Table 1)It was found that when Aid 6 C 5 was cul-tured with primed spleen or mesenteric lym-ph node cells from C 57 BL/6 J mice im-munized with Trichosanthin 8 weeks before,it was able to stimulate the secondary anti-Trichosanthin responses in the absence of an-tigen .When AId 6 C 5 was cultured with theprimed cells in the presence of Trichosanthinat an antibody-inducible dosage,the antibodyresponse was slightly suppressed rather thanenhanced.Due to the monoclonal nature ofthe antiidiotope antibody,it is thus sugges-ted that single ATd could be either stimula-tive or suppressive under different condi-tions. AId 6C5 further reacted strongly withanother 2 MoAbs of the other MoAbs tested(Fig.1).They were TE 4 of IgE class and2 A 1 of IgG_1 subclass.From our previous workit was shown that the three of them all recog-nized the same determinant on Trichosanthin.However,AId 6 C 5 reacted weakly or notreacted at all with the other 4 MoAbs reac-ting with the same determinant.It seems toindicate that IgE can share Id with other Igclasses and that the presence of different Idson IgEs recognizing one and the same deter-minant.Preincubation of the three MoAbswith AId 6 C 5 could lead to the blocking oftheir binding to the antigen,though not com-pletely (Fig.2).It seems that the Id re-cognized by AId 6 C 5 is located at antigenbinding site or at a position very close to it.